In a typical grinding machine, the rotor or output shaft of the machine and a suitable grinding cup are engaged and rotate together providing a means for sharpening and/or re-shaping drill bits. Over time, however, the connection between the output shaft and the grinding cup wears causing the grinding cup to become loose in its “seat” in the end of the shaft, making the grinding cup more likely to fall out. As well, the loose fitting connection between the grinding cup and the output shaft decreases the overall efficiency of the grinding machine. Replacing the entire rotor shaft, however, can be both costly and time consuming.
Various adapters or chucks are known for mounting a grinding cup to the shaft of a grinding machine. For instance, U.S. Pat. No. 6,835,114 to Sjolander discloses a holder device (see FIG. 14) for anchoring a grinding cup to an output shaft of a grinding machine. The body portion of the holder device has a centrally disposed cavity that is sized and shaped to permit the holder device to be detachably connected to the output drive shaft of the grinding machine. Retaining means are provided on either the output drive shaft or in the adapter (or a combination of both) to detachably retain the holder device so that it will not fly off the output shaft during use. The centrally disposed cavity has a drive section formed at the end thereof for drivably engaging the end of the output shaft. The drive section preferably has a hexagonal cross-section which is specifically adapted to engage with a specific output shaft of a grinding machine having a hexagonally-shaped end. Accordingly, the holder device is not easily adaptable to drivingly engage various forms of output shafts.